Theoretical topological analysis of the electron density in Picolyl N-Heterocyclic Carbene Triruthenium carbonyl cluster: [Ru3(μ-H)2(μ3-κ3C2,NHCpyCH2ImMe)(CO)8] (ImMe=3-methylimidazol-2- ylidene)

Abstract

A number of topological parameters of the electron density of bonding interactions in the Picolyl N-Heterocyclic Carbene Triruthenium carbonyl cluster [Ru₃(μ-H)₂(μ³-κ³C₂,NHCpyCH₂ImMe)(CO)₈] has been calculated and interpreted under the perception of the Quantum theory atoms in molecules (QTAIM). These results have allowed a comparison between topological properties of different atom-atom interactions. The QTAIM theory recognizes the existence of a bond path in only one of the Ru(1)-Ru(3) edges. Consequently, an interaction of 5c-6e type is proposed to exist in the Ru₃H₂ core. The three atoms N-C-C bridge that spans the Ru(1)-Ru(3) edge is not as efficient as bridges comprising one atom, such as hydride in order to delocalize the electronic density of the bridged metal atoms. All topological parameters calculated for the three existing Ru-C bonds between the metal atoms and the NHC ligand are similar, and they confirm that these interactions are pure σ bond. The analysis of the topological parameters of the Picolyl and NHC ligands bonds confirms the existence of Ï€-electron delocalization within the six-membered ring for Picolyl ligand and hindered Ï€-electron delocalization within the five-membered ring of NHC ligand with some double-bond character in the interaction of the carbine C atom with the adjacent N atoms.